The invention relates to photographic cameras and equipment and to seals and more particularly relates to camera front seal assemblies.
Seals have long been used in telescoping and retractable lens barrels to keep out water and dust and to block light. Many such seals are relatively hard and fit tightly between close fitting parts. This is an effective approach, but costs can be reduced if tolerances are increased. This desire for reduced costs has lead to the use of seals that have a flexible portion that flaps back and forth during use. This approach is also effective, but the seal is subject to some constraints, which are necessary to keep the flapping portion from being too fragile. A further limitation, in some instances, is that of providing adequate thickness of seal to block entry of light. A further limitation is the necessity of a shaping the seal in some manner that allows the seal to be held in position during use. It is not difficult to make seals having relatively complex shapes, however, a burden can be presented by the requirement of keeping such seals in inventory until needed. Still another limitation is that many seals impose a frictional load that must be overcome during relative movement of parts.
U.S. Pat. No. 6,038,087 discloses a camera having a light sealed with a pair of inclined fins that are in sliding contact with the surface of a relatively movable part.
The provision of light locks between rotating parts is well known. U.S. Pat. No. 3,904,284 discloses a labyrinth seal between a core and the wall of a film magazine.
It would thus be desirable to provide a seal assembly that can block light, yet is simple and inexpensive and does not have to flap during use.
The invention is defined by the claims. The invention, in broader aspects, provides a camera seal assembly that has a first retainer having an opening. The first retainer defines an axis extending through the opening. A second retainer is disposed in fixed relation to the first retainer. The second retainer faces the first retainer in spaced relation along the axis. A barrel extends through the opening. The barrel has a cylindrical barrel wall. A collar has a side wall facing the barrel wall. The barrel is movable relative to the collar. A stack of alternating lesser and greater rings is disposed between the first and second retainers and between the barrel wall and side wall. The lesser rings are movable relative to the greater rings in directions radial to the axis. The stack has a centered state, in which each lesser ring more closely adjoins the barrel wall than the side wall and each greater ring more closely adjoins the side wall than the barrel wall.
It is an advantageous effect of the invention to provide an improved seal assembly that can block light, yet is simple and inexpensive and does not have to flap during use.